Every year, millions of Americans visit "alternative" or "complementary" providers such as chiropractors, acupuncturists, massage therapists and naturopaths for health-related advice or treatment. Some health care insurers have taken notice of the growing popularity of alternative providers and have begun to cover at least some of the services they offer. Although offering a broader range of health care options to consumers has merit, decisions about which services should or should not be covered are being made in the absence of information about their safety, effectiveness and cost. In fact, little is known about even the most fundamental aspects of alterative providers practices: what problems they see and how they respond to these problems. The primary goal of the proposed study is to provide a comprehensive description of alternative providers' practices: the number and types of patients they see, the types of problems they treat, the diagnostic and therapeutic methods they employ, and the amount of time they spend with each patient. Detailed information of this type has been widely available for medical practice for two decades but has not yet been assembled for alternative providers. For types of alterative providers will be studies: acupuncturists, chiropractors, massage therapists and naturopaths. A representative sample of one hundred providers of each type will be included in the study: 50 from Washington state and 50 from Massachusetts. Each provider will be asked to provide information about their practices (e.g., patients seen and hours worked in a typical week) and to complete encounter forms for 20 consecutive patients they see during a specified time period. The encounter forms will capture sociodemographic information about the patient (e.g., age, gender, race) as well as information about the visit (e.g., reason for visit, tests, diagnosis, treatments, visit duration, source of payment, referral). This information will permit description of the role that each type of alternative provider is currently playing in today's health care system and comparisons of each of their roles with one another and with that played by medical doctors. This study will provide unique information about alternative providers that will help consumers, health care managers, insurers, policymakers, and researchers determine how to most sensibly integrate alternative providers into the health care system of the future.